This invention relates generally to paint spray systems and, in particular, to a pneumatically controlled paint spray system.
Powder paint has been developed to minimize environmental concerns by avoiding use of solvents found in liquid paint. In powder paint operations, fine particles of colored powder are positively charged upon ejection from a spray gun. The ejected powder is attracted to and is electrostatically bonded to a negatively charged work piece disposed in a paint booth. This electrostatic bonding temporarily affixes the powder to the work piece. Subsequent heat treating melts the powder and thus permanently affixes it to the work piece.
During powder painting operations, some of the fine particles of powder do not bond to the work piece and become suspended in the atmosphere in the vicinity of the paint booth. Since existing systems for applying powder paint utilize either electrically controlled or hydraulically controlled spray gun mechanisms, complex and costly shielding must be provided to maintain a spark free environment in and around the paint booth in order to prevent an explosion of the suspended powder. Furthermore, both electrically controlled spray gun mechanisms and hydraulically controlled spray gun mechanisms are very expensive and complex. In addition, the suspended powder results in frequent cleaning of spray gun mechanims that are electrically controlled or hydraulically controlled to prevent them from malfunctioning.